This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A378389 #12 Nov 28 2024 11:11:37 %S A378389 2,4,9,8,0,9,1,5,4,4,7,9,6,5,0,8,8,5,1,6,5,9,8,3,4,1,5,4,5,6,2,1,8,0, %T A378389 2,4,6,1,5,5,6,5,8,8,0,8,2,5,9,7,9,3,4,3,8,1,0,9,3,3,8,4,7,3,5,9,4,3, %U A378389 0,3,9,3,1,4,7,4,5,8,7,9,0,9,9,1,5,2,1,7,9,8 %N A378389 Decimal expansion of the dihedral angle, in radians, between any two adjacent faces in a tetrakis hexahedron. %C A378389 The tetrakis hexahedron is the dual polyhedron of the truncated octahedron. %H A378389 Paolo Xausa, <a href="/A378389/b378389.txt">Table of n, a(n) for n = 1..10000</a> %H A378389 Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetrakis_hexahedron">Tetrakis hexahedron</a>. %F A378389 Equals arccos(-4/5). %F A378389 Equals 2*A195729. - _Amiram Eldar_, Nov 27 2024 %e A378389 2.498091544796508851659834154562180246155658808... %t A378389 First[RealDigits[ArcCos[-4/5], 10, 100]] (* or *) %t A378389 First[RealDigits[First[PolyhedronData["TetrakisHexahedron", "DihedralAngles"]], 10, 100]] %Y A378389 Cf. A378388 (surface area), A374359 (volume - 1), A010532 (inradius*10), A179587 (midradius + 1). %Y A378389 Cf. A156546 and A195698 (dihedral angles of a truncated octahedron), A195729. %K A378389 nonn,cons,easy %O A378389 1,1 %A A378389 _Paolo Xausa_, Nov 27 2024